Method and apparatus for treating waste

ABSTRACT

An apparatus for treating waste includes a vessel and DC and/or AC plasma torches with a variable flame mounted with the vessel. The flames generated by the torches can be adjusted depending on the characteristics of the waste being treated. Waste can be introduced into the vessel and heated with energy from the flame. The energy can melt or vitrify the inorganic portion of the waste and gasify and dissociate the organic portion of the waste. This dissociation can destroy the hazardous or toxic constituency of the waste.

PRIORITY CLAIM

The present application claims priority as a continuation to U.S.application Ser. No. 10/820,651, filed Apr. 8, 2004, which is acontinuation of U.S. Provisional Application Ser. No. 60/554,879, filedMar. 19, 2004. The priority applications are hereby incorporated byreference.

BACKGROUND

This invention relates to the treatment of waste material, and, moreparticularly, to the controlled thermal destruction of hazardous andnon-hazardous materials.

Placing waste material in landfills was previously the accepted methodof disposal. When the consequences of landfill disposal wereinvestigated more closely, public opposition and regulatory pressuresrestricted the landfill practice and compelled the industry to insteademploy incineration, the only other then-available technology that waseconomical and appeared to address the disposal problems.

Incineration proved useful where landfill space was unavailable or tooexpensive, but, for a number of reasons, it also was generallyinadequate. The basic nature of medical waste, for example, createssubstantial problems for incinerators. One of the major problemsencountered in using incinerators to combust medical waste is theheterogeneity of the waste material. This problem prevents theincinerators from maintaining a sufficiently high constant temperatureto completely treat all of the organic and inorganic material in thewaste, which can result in hazardous bottom or fly ash. For example, afirst bag of such waste may be filled with containers of fluids, bloodsoaked bandages, and sharp objects (syringes, glass, metal surgicaltools, and the like), while a second bag may contain mostly plastics,paper, packing material, pads, surgical gowns, rubber gloves, and thelike. These two bags, fed independently into an incinerator, wouldcreate totally different combustion conditions. The first bag wouldquench and cool the combustion process, while the second bag wouldaccelerate and raise temperatures.

During the low temperature cycle, products of incomplete combustion(pollutants) and potentially hazardous organic materials, such asdioxin, furan, and greenhouse gases, may be generated and ultimatelyreleased into the atmosphere. During the high temperature cycle,particulate, nitrogen oxide, and metal oxide emissions increase,including hexavalent chromium, a known carcinogen.

Shredding waste before feeding it into the combustion vessel canhomogenize and mix the waste, but it may not be acceptable because ofthe potentially infectious nature of the waste and the inherent problemof disinfecting a shredder having numerous internal components and smallconfined places where infectious material might collect and escapedisinfection. Moreover, some states may have laws prohibiting bags ofinfectious waste from being opened prior to their final processing.

Compounding the problem of temperature control within incinerators isthe batch method of feeding that is commonly used (in contrast tocontinuous feeding). In this method, a ram system is normally used topush a charge of waste into a combustion vessel. Because the incineratorrelies on the waste itself for fuel, as the waste combusts, vesseltemperatures vary as the amount of combustible waste in the vesselchanges. This problem is especially pronounced at start-up andshut-down. Temperatures also vary with changing feed rates andincinerators can operate poorly at reduced feed rates.

It can be important to achieve and maintain high temperatures becausethe treatment of inorganic waste components commonly found in medicaland other waste streams requires such temperatures. High temperaturesare required to melt stainless steel and borosilicate glass used inlaboratories, for example, and incinerators may require fossil fueladditions to supplement the combustion process to reach thesetemperatures.

The destruction of organic waste also requires high temperatures, butinstead of melting at high temperatures, such waste decomposes and burnsif sufficient air is present. The combustion process can beself-sustaining only if enough heat energy is released during theprocess to cause additional material to decompose. This can be a problemin incinerators, however, and especially when wet and inorganicmaterials are present in the feed. Under such conditions, it may not bepossible to maintain a high, continuous operating temperature.

Apparatuses that have used plasma torches to improve on the low andvarying temperature problem have only achieved a partial solution. Forexample, a known ram (or batch) feed system causes significant variationin gas flow rates and temperatures, and includes no precautionarymeasures to hold the exit gas temperature at a safe high level at whichreformation of complex organic compounds is minimized. The off-gaspiping, for example, is composed of stainless steel and it leads to asteel cyclone for particulate collection, which causes the gastemperature to drop into a sufficiently low range (i.e., into theapproximately 350-500° C. range). When the temperature of the gas dropsto such temperatures, significant reformation of undesirable organiccompounds, and particularly polycyclic aromatic hydrocarbons (PAH's),can occur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an apparatus for treating waste.

FIG. 2 is a partially schematic view of an apparatus for treating waste.

FIG. 3 is a partially schematic view of a particulate monitoring system.

FIG. 4 is a flow diagram of a method for treating waste.

FIG. 5 is a flow diagram of a method for treating waste.

FIGS. 6A and 6B are a flow diagram of a method for treating waste.

FIG. 7 is a flow diagram of a method for treating waste.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, a waste processing system 5 is describedhereinafter in detail. The waste processing system 5 may be used totreat any type of product that may be decomposed upon the application ofenergy. For example, it may be used to treat municipal solid waste,medical waste, thermal batteries, fly and bottom ash, and militarywaste, including weapon components. The waste processing system 5 mayalso be used to treat other waste such as PCB-contaminated materials,industrial and laboratory solvents, organic and inorganic chemicals,pesticides, organo-chlorides, refinery waste, office waste, cafeteriawaste, facilities maintenance waste such as wooden pallets, oils,grease, discarded light fixtures, yard waste, wastewater sludge, andpharmaceutical waste. The waste product, furthermore, may includeorganic and inorganic components and may be in the form of solid and/orliquid material.

For ease of reference, the figures and description sometimes refer tothe waste as medical waste, which may include, for example, bags ofinfectious waste, including blood-soaked sponges, bandages, containersof sharps such as needles, razors, scalpels, and other instruments. Itis to be understood, however, that unless stated otherwise or unless itis clear from the context, when reference is made to medical waste orsome other particular type of waste product, it also encompasses othertypes of waste.

Referring to FIGS. 1 and 2, the waste processing system 5 includes awaste feed system 10, such as the feed system disclosed in U.S. Pat. No.5,534,659, which is hereby incorporated by reference herein. The feedsystem 10 feeds waste “W” into a waste processing or pyrolysis vessel20. The feed system 10 includes a charging hopper 11 positioned above afeed hopper 12. An airlock door 13 functions as a sliding cover for thecharging hopper 11. When waste is to be placed in the charging hopper11, the door 13 is moved to the opened position as shown. After chargingis completed, the door 13 is closed in the direction of arrow “A” tocover the charging hopper 11. A second, alternately opening, slidingairlock door 14 separates the charging hopper 111 from the feed hopper12 when in its illustrated closed position. To charge the feed hopper12, the door 14 is opened in the direction of arrow “B” while the door13 is closed (to prevent the release of any emissions from the feedhopper 12 into the environment and to minimize the introduction of airinto the feed hopper 12). Each door 13 and 14 can be provided withappropriate seals that cooperate with seals in the side walls of thecharging hopper 11 to prevent emissions from leaking out of the feedsystem 10.

Inorganic “powdered” type waste streams such as incinerator ash,electric furnace dust or waste water treatment plant sludges, or othertypes of waste, may be introduced into the feed hopper 12 in analternative manner. A third sliding airlock door 14A is provided at theside of the feed hopper 12. The door 14A can be operated in a mannersimilar to the doors 13 and 14. The door 14A, furthermore, can beinterlocked such that it cannot be opened when either of the slide doors13 and 14 is open.

A purging system 41 can be provided to introduce a gas, such asnitrogen, into the feed hopper 12 and/or at other points in the feedingsystem 10. The purging system 41 can be comprised of a source ofnitrogen, such as a nitrogen tank, tubing interconnecting the nitrogensource and the feed hopper 12, and appropriate valving to regulate thequantity of nitrogen introduced into the feed hopper 12 and the timingof the purging. In addition, the purging system 41 can be selectivelyoperated along with the sliding doors 13 and 14. In this manner, thepurging system can purge hazardous emissions that may become containedin the feeding system 10 before or while the doors 13 and 14 are opened.The purging system 41 can also limit the amount of combustible gasesthat were generated in the pyrolysis vessel 20 from escaping from thevessel 20 or the feed hopper 12. The nitrogen gas is vented to thevessel 20 as further described below.

The interior of the feed hopper 12 can be relatively open and free ofobstructions and contain minimal crevices or cracks in which infectiousmaterial can accumulate. This design can help allow the feed hopper 12and a cantilevered screw-type auger 16 to be disinfected by adisinfectant system 21. The disinfectant system 21 includes a supplycontainer 22 in which an appropriate disinfectant is retained. Forexample, a disinfectant comprising a 6% solution of hydrogen peroxidemay be used. The container 22 is connected by a supply line 23 to aninjector nozzle 24 mounted within the feed hopper 12. The disinfectantis pressurized by a pump 25.

It is desirable that the nozzle 24 is arranged to ensure that the entirearea within the feed hopper 12 may be subjected to the disinfectantspray to help prevent or minimize the release of toxic or hazardousemissions when the door 14 to the feed hopper 12 is opened. In analternative embodiment, several nozzles may be used and each may bepositioned to spray disinfectant on a different portion of the feedhopper 12. Also, while it is desirable to spray disinfectant on theentire area within the feed hopper 12, it may be sprayed on less thanthe entire area. After it is applied, the disinfectant drains into thepyrolysis vessel 20 and is processed as waste.

A vent system 15 can be provided between the feed hopper 12 and thepyrolysis vessel 20. The gas introduced by the purging system 41, e.g.nitrogen gas, and any toxic/hazardous gases can be drawn into thepyrolysis vessel 20 through the vent system 15. The gas can be drawn,for example, as a result of a vacuum created by a draft fan 19 and/orejector-venturi quencher 65 disposed downstream of the feed system 10(see FIG. 1).

After the waste is placed into the charging hopper 12, the auger 16shreds, mixes, compresses, and extrudes the waste charge into a feedtube 17. The auger 16 can be driven by a motor 101, such as a hydraulicmotor with a variable speed drive. The feed tube 17 may be surrounded bya water-cooled jacket 17′ to help keep the feed tube 17 cool and to helpmaintain the structural integrity of the feed tube 17, which can beexposed to the elevated temperatures in the vessel 20. The water-cooledjacket 17′ may be connected to a water source with a pump. The water canbe circulated by the pump in two directions, from the side of thewater-cooled jacket 17′ closest to the vessel 20 to the opposite side,and from the side of the water-cooled jacket 17′ closest to the feedhopper 12 to the opposite side. In the alternative, water can becirculated in both directions. Also, the water may be circulated in twoloops, where one loop circulates water to the portion of theWater-cooled jacket 17′ closest to the vessel 20, and the other loopcirculates water to the portion of the water-cooled jacket 17′ closestto the feed hopper 12.

A feed tube slide gate 18 (which also may be water cooled) is providedtowards the inlet port of the pyrolysis vessel 20 to isolate part of thefeed tube 17 from heat generated in the pyrolysis vessel 20. In thealternative, the slide gate 18 may be located near or at the outlet ofthe feeding hopper 12 (i.e. at the beginning of the feed tube 17). Theopening and closing of the gate 18 may be automatically controlled andcan be interlocked such that the gate 18 cannot be opened when either ofthe slide doors 13 and 14 is open.

In operation, the auger 16 can form the liquid and solid waste togetherinto a dense cylindrical plug 102 in the feed tube 17. The waste can beintroduced into the pyrolysis vessel 20 through the feed tube 17 (whenthe gate 18 is open) at a controlled and desirably continuous rate.Introducing the waste into the vessel 20 in this manner can expose acontrolled amount of surface area of the compacted waste to thepyrolysis process and help regulate the formation of gases generated asa result of the pyrolysis. The auger 16 can help minimize theentrainment of air pockets in the waste stream being fed into the vessel20.

The waste can be introduced directly into a slag pool 103 near thebottom of the vessel 20 or it can be introduced directly into the plasmaflame or at other points in the vessel 20. It should be understood,however, that the particular feeding system employed is generallyapplication specific. It should also be understood that any type ofknown means, or any means subsequently developed, for feeding ortransferring the waste to the vessel 20 may be employed with the wasteprocessing system 5 described herein.

Organic and inorganic waste may be treated separately or simultaneouslywith the waste treatment system 5 described herein. To process the wasteseparately, the inorganic and organic waste streams are separatelyintroduced into the feeding system 10 and fed into the vessel 20. Toprocess the waste streams simultaneously, the waste streams aresimultaneously introduced into the feeding system 10 where the waste isshredded and mixed to create a homogenous mix, which is then fed intothe vessel 20. Equal or non-equal portions of organic and inorganicwaste can be treated with the waste processing system 5 describedherein.

The desired rate at which the waste is fed into the vessel 20 isdependent, for example, on the characteristics of the waste, the plasmaenergy available from the plasma generating system and the temperatureand oxygen conditions within the pyrolysis vessel 20. The feed rate maybe initially calculated based on an estimation of the energy required toprocess the specific waste type being treated. The desired feed rate isdetermined by actual operation of the system, and is selected tomaintain a desired average temperature within the pyrolysis vessel 20.AC plasma torches 35A and 35B, described in greater detail below, cangenerate a flame “F”, which inputs energy into the pyrolysis vessel 20that is absorbed by the waste during the pyrolysis process. An excessivefeed rate maintained for a period of time can cause the interiortemperature of the pyrolysis vessel 20 to decrease or increase dependingon the waste being treated. An inappropriate feed rate can cause thepyrolysis vessel 20 to overheat or pressurize. Accordingly, the desiredfeed rate is selected to achieve the desired average temperature, whichcan be in the range of about 1,370° C. to 1,850° C. An example of awaste processing system is one that is capable of processingapproximately 1000 pounds of waste per hour, using a 500 kW AC plasmatorch. A system including an AC torch of about one-half of this powerrating and a proportionally smaller processing vessel processes about500 pounds per hour.

The vessel 20 is a plasma arc furnace and can be designed to withstandtemperatures of up to about 1,850° C. in a reducing atmosphere. Forexample, the vessel 20 can be made of carbon steel, stainless steel,and/or other materials, such as hastelloy. The vessel 20 includes a mainsection 28, which can be squarely or cylindrically shaped or shaped insome other manner. The vessel 20 also includes a flat roof section 29and a lower section 30, which includes a bowl-shaped portion. Thesections are assembled at flanged joints 31 and 32 so as to provide anairtight structure. The upper structure surrounding the open space 810is lined with alumina refractory. The bowl-shaped portion of the lowersection 30 is lined with chrome-containing alumina refractory, which caninhibit the erosion caused by the slag and molten metal contained in theslag pool 103 (further described herein).

The vessel 20 is generally a horizontally oriented structure, which hasseveral advantages over other structures. For example, it can reduce thedistance between the AC torches 35A and 35B and the bowl-shaped lowerportion, which can facilitate melting and tapping as further describedbelow. In addition, the torches 35A and 35B can therefore be mountedwithout penetrating the open space 810 of the vessel 20.

The vessel 20 can be optimally shaped based on the characteristics ofthe waste to be treated. For example, if the waste will include apercentage of inorganic material, it can be shaped with a bowl-shapedlower portion. As further described below, as the inorganic material isfed into the chamber, it is melted or vitrified and can form a slag pool103 contained by gravity in the bowl-shaped lower portion. Accordingly,the volume of the bowl-shaped lower portion can be sufficiently large tocontain the slag pool 103 in operation.

If the waste will include a percentage of organic material, for example,the vessel 20 can be shaped with an open area 810. As further describedbelow, as the organic material is fed into the vessel 20, it isdissociated into its elemental components and gasified within the vessel20. The open area 810 can be sufficiently large to allow the organicwaste to gasify and circulate around the vessel 20 (absorbing the energyfrom the flame “F”) and dissociate into its elemental components beforeexiting the vessel 20.

If the waste will include a percentage of organic material and apercentage of inorganic material, it can be shaped with a bowl-shapedlower portion and an open area 810. An exemplary vessel processing 5tons of organic and/or inorganic waste per day has a total volume ofabout 50 cubic feet, has a bowl-shaped volume of about 8 cubic feet, andits overall dimensions are about 62 inches high, and 97 inches square.The optimal dimensions of the vessel 20, however, are applicationdependent.

The AC plasma torches 35A and 35B can be mounted through the torchreceptacle openings 36 of the vessel 20. While two torches areillustrated, one or more torches can be used. An exemplary AC plasmatorch is manufactured by The Institute for Problems ofElectrophysics—Russian Academy of Sciences (IPE-RAS), located in St.Petersburg, Russia. Desirably, the torches 35A and 35B are mounted sothat the bodies of the torches do not penetrate the interior of thevessel 20. By mounting the torches in this fashion, torch-cooling loadsmay be decreased thus increasing operating thermal efficiency andlowering cost. Moreover, in the event of a water line break inside thetorches 35A and 35B, the water will not flow into the vessel 20. Inother embodiments, however, the body of the torches 35A and 35Bpartially or fully penetrate the vessel 20.

Either torch, 35A or 35B, or both, may be activated during operation ofthe waste processing system 5. The other torch can be provided to reduceor eliminate system down time while replacement of torch electrodes isperformed on the first torch. When one torch is being replaced or fixed,the other can be used. The non-operating torch can be isolated from thevessel 20 by means of a slide gate 155. This can help facilitatemaintenance of the torch and electrode replacement without significantimpact on the operating schedule.

In other embodiments, however, only one torch may be provided and used,or more than two torches may be provided and used. In addition, the twoor more torches can be operated simultaneously or in an alternating orintermittent manner as long as power supplies are provided for eachactivated torch.

The torches 35A or 35B (the torch 35A is shown in operation in theembodiment shown in FIG. 2) emit a plasma flame “F” with temperaturesexceeding about 6,000° C. The flame “F” provides energy, which heats theinterior of the vessel 20 to a uniform temperature desirably in therange of about 1,370° C. to about 1,850° C. A non-transferred type torchcan be used for treating medical waste that can be high in organics. Incomparison to transferred type torches, non-transferred type torches canoffer the advantages of simpler mechanical control requirements ascontinual torch motion is not required, greater bulk gas heatingcapability, increased arc stability, especially during the heat upperiod, simplified furnace design, and overall greater systemreliability. The arc in non-transferred type torches, furthermore, doesnot become “short-circuited” when waste is introduced into the system.The plasma heating system 35 further includes a power supply, supportingutilities such as a plasma gas compressor, and a cooling system.

The waste processing system 5 can employ an AC plasma torch. An AC torchhas an inherently stable plasma plume that is more diffuse and densecompared to a DC torch. The wide plume enhances the ability of the torchto achieve molecular dissociation of the hazardous components in thewaste being treated, as further described herein. In addition, an ACtorch typically can have lower operating costs than a DC torch. Theelectrodes used in AC torches cost less than the electrodes used in DCtorches. AC torches, furthermore, have an inherently higher electric tothermal efficiency. When the flame is varied on a DC plasma torch,furthermore, the life of the torch electrodes can decrease significantly(because DC torch electrodes are designed with a fixed torch gaspressure). On the other hand, when the flame is varied on an AC plasmatorch, such as by varying the current as further discussed herein, thelife of the torch electrodes is not significantly affected.

DC torches are typically positioned relative to a plasma arc furnacesuch that the body of the torch penetrates the furnace. This exposes thetorch body to the high temperatures generated in the furnace and, inturn, requires that a coolant (e.g., water) be continuously circulatedthrough the torch body. As a result, heat energy generated in thefurnace can be lost to the torch and torch body. AC torches, on theother hand, can be mounted relative to the furnace such that the torchbody does not penetrate the furnace. Accordingly, AC torches can requireless circulating coolant and can allow for a greater amount of theenergy generated in the furnace to be productively used.

When the electrodes of a DC torch need to be replaced, the entire torchmust be removed from the system and a torch sealing device may betemporarily installed to fill the void where the torch is removed. An ACtorch, in contrast, does not need to be removed from the system when theelectrodes need replacement. The electrodes of an AC torch can bereplaced in situ. Despite some of the advantages of using an AC torch,however, one or several DC torches may be used with the waste processingsystem 5 described herein, alone or together with an AC torch.

The waste processing system 5 can allow the plume length of the flamesand power generated by the torches 35A and 35B to be varied depending onthe type of waste being treated (by controlling the type of torch gas158, the flow rate of the torch gas 158, and torch current 159). Forexample, the torch power output can be regulated by the process monitorand controls 50 such that four current settings are provided to anoperator to adjust the flames. The settings can vary, for example, by afactor of 5. Any number of settings, however, may be provided, and thesettings can vary by factors other than 5.

When processing organic materials, for example, the flame can bevariable and can be adjusted to be wider and shorter. In this manner,the flame can cover a larger area within the vessel 20. The flame thuscontacts a greater portion of the gases circulating in the vessel 20,which can increase the efficiency of the destruction of organicmaterials. In addition, the flame can contact a greater surface area ofthe slag pool, which can facilitate the melting of inorganic materials.

The desirable flame size and shape is implementation dependent and candepend, for example, on the waste being treated and the shape anddimensions of the vessel. An exemplary flame shape is roughly oval andapproximately 6 inches in diameter by 2 feet long. An access and viewingport 38 is provided in the central section of the pyrolysis vessel 20.An operator can monitor the flame through the port 38.

In operation, as the waste material is introduced into the vessel 20, itabsorbs energy by convection, conduction, and/or radiation from theplasma flame “F”, the heated refractory lining, and the heated gasescirculating in the vessel 20. Generally speaking, the energy melts orvitrifies the inorganic portion of the waste (such as non-toxic metals,toxic heavy metals, ceramics, glasses, soil, and ash) and gasifies anddissociates the organic portion of the waste. Thus, the energy from thetorches 35A and 35B can be used for the purpose of melting or vitrifyinginorganic waste and gasifying and dissociating organic waste,simultaneously or non-simultaneously.

Turning first to the inorganic portion of the waste material, as it ismelted, it forms the slag pool 103 of glass-like slag and, in someinstances, a metal layer, which may be separable. To remove the glassyslags from the pyrolysis vessel 20, the slag pool 103 may be drainedthrough slag taps 42 and 46 (not shown) which can be positioned at thesides of the vessel 20. The taps 42 and 46 can be of a suitable diameterto allow tapping of the glassy slag at a greater rate than accumulationof the glassy slag. The taps 42 and 46 can operate at the same time orat alternate times. Desirably, however, the taps 42 and 46 are operatedsimultaneously when a significant percentage of inorganic waste materialis being processed because the time necessary to drain the slag pool 103can be decreased compared to when only one tap is operated. The taps 42and 46 can be selectively used, rather than continuously used, in orderto minimize energy loss from the pyrolysis vessel 20 during tapping.Accordingly, the taps 42 and 46 can be sealed during standby periods bya tap positioning device (“tap plug”) 43 which closes the taps 42 and46.

In other embodiments, only one tap may be provided and used or more thantwo taps may be provided and used. In addition, the taps can bepositioned at locations of the vessel 20 other than at the sides. Forexample, a tap 157 can be located toward the bottom of the vessel 20.Furthermore, other means may be used to drain the slag pool 103 from thevessel 20.

When a significant percentage of inorganic waste is being processed,nitrogen can be used as the torch gas, which can reduce or eliminate theformation of oxides in the slag pool 103. This can help facilitate thedraining of the slag pool 103 because the metals remain in elementalform (rather than forming metal oxides).

When spent refinery catalysts are being processed, for example, severaladditives may be used to help treat the waste. Such catalysts generallyhave a relatively high Alumina (i.e. Al₂O₃) content. Because of the highAlumina content, the refractory lining the vessel 20 may be eroded ordegraded during the treatment of such catalysts. This degradation can beavoided or minimized if the catalyst waste is treated in a reducingatmosphere such that the Alumina content is reduced. Accordingly,reducing agents, such as waste oils, petroleum coke, medical waste, orother organic hazardous wastes or material containing high levels ofcarbon, can be added to the waste stream during the treatment of spentrefinery catalysts. The reducing agents can also help maintain thefluidity of the slag pool 103 and facilitate tapping.

The fluidity of the slag pool is generally dependent on the compositionof the slag pool 103. The composition of the slag pool 103 generated asa result of treatment of the spent catalyst waste can be controlled bythe addition of a fluxing agent that contains calcium and/or silica tothe catalyst waste stream. Exemplary fluxing agents include incineratorfly ash, spent materials from the waste water treatment system, and CaF₂sludges generated, for example, by the semiconductor industry. If CaF₂sludge is used as the fluxing agent, however, the amount added to thecatalyst waste stream can be controlled to minimize the generation of HFgas.

The glassy slag drained through the taps 42 and 46 can be drained intotwo separate solid residue handling systems 80 and 81. For simplicity,only solid residue handling system 81 is illustrated in FIG. 2. The slagcan be drained into a sealed water tank 80 (with continuouslyregenerated water). The solid residue handling system 81 can alsoinclude a conveyor or other suitable device 82 and a bin 85 fortransport and disposal.

In operation, the molten material (glassy slag) passes through the taps42 and 46 and into the slag removal system, such as the sealed watertank 80 and associated components, where the material can be rapidlyquenched (and solidified), which causes it to fracture into smallerpieces. The solid glassy slag can be essentially inert because the heavymetals are bound within it. Consequently, the glassy slag can resistleaching in the solid state. The solid glassy slag may then betransported from the sealed water tank 80 to the disposal bin 85 by theconveyor 82.

The glassy slag may also be drained through the taps 42 and 46 intowater-cooled slag tap carts, such as cart 156, which are removed fromthe vessel after the slag is cooled and solidified. As a furtheralternative, the slag can be drained into other specially designedcomponents contained in the cars, such as molds insulated by sand.

The solid glassy slag, which is benign and does not require landfilling,may then be used for a number of commercial applications, including roadconstruction, concrete aggregate, blast cleaning, and fiberglass. It canalso be formed into decorative tiles, or used in conjunction withbuilding materials to create lightweight pre-engineered homeconstruction materials.

Over a period of time, a layer of metals may accumulate at the bottom ofthe slag pool 103. Certain metals such as iron do not react readily withthe silicates contained in the slag pool 103. The glassy materialabsorbs some of these metals, but the metals may accumulate if a largeamount is present in the waste stream. The metals can be drained throughthe taps 42 and 46 and processed as described above.

Turning now to the organic portion of the waste material, as it isheated, it can become increasingly unstable until it eventuallydissociates into its elemental components, mainly solid carbon (finecarbon particulate) and hydrogen gas and is gasified. Oxygen, nitrogen,and the halogens (typically chlorine) are also liberated if present inthe waste in a hydrocarbon derivative. This gasification anddissociation process is generally called molecular dissociationpyrolysis. Pyrolysis is a process by which intense heat operating in ananaerobic or extremely low oxygen environment dissociates molecules, ascontrasted with incineration or “burning.”

The time required to achieve dissociation can vary slightly fordifferent materials, but is typically well under a second and oftenmilliseconds for most compounds at 1100° C. Thus, hazardous waste, whichis generally made up of complex organic compounds including hydrogen,oxygen, nitrogen and carbon atoms, can be disassociated into itselemental constituents. This dissociation can destroy the hazardous ortoxic constituency of the waste material.

Upon dissociation, oxygen and chlorine can be free to react with thecarbon and hydrogen produced and could theoretically reform a wide arrayof complex (and potentially hazardous) organic compounds. Suchcompounds, however, generally cannot form at the high temperaturesmaintained within the vessel 20 at which only a limited number of simplecompounds may be stable. The most common and stable of these simplecompounds are carbon monoxide (formed from a reaction between the freeoxygen and carbon particulate), diatomic nitrogen, hydrogen gas, andhydrogen chloride gas (when chlorine is present).

There is normally an insufficient amount of oxygen liberated from thewaste material to convert all of the fine particulate carbon to carbonmonoxide gas. While moisture in the waste may liberate additionaloxygen, unless the waste moisture content is uniformly distributedthroughout the waste and exceeds at least about 30% by weight, theconversion of the solid carbon to carbon monoxide gas may not bemaximized. As a result, fine carbon particulate can be entrained andcarried out of the flame “F” by the hydrogen-dominated gas stream.

To maximize the conversion of solid carbon to carbon monoxide gas, anadditional source of oxygen may be used. Accordingly, the wasteprocessing system 5 described herein includes a means for injecting anoxidant into the system in an amount effective to convert a portion ofthe carbon particulate to carbon monoxide. The injection means can be anoxidant supply system 53 which includes a steam generator 53′ and asteam valve 54 that is opened in a controlled manner (as furtherdescribed below) to supply steam to injectors 45. The injectors 45, inturn, inject predetermined amounts of steam into the pyrolysis vessel 20and gas vent 40. In other embodiments, different oxidants such as air oroxygen gas may be used as the oxidant. In addition, other means may beemployed to introduce the oxidant into the vessel 20. For example, theoxidant may be introduced through the torches 35A and 35B or may bemixed with the waste in the feed tube 17.

The steam injected into the system can convert the free carbon intoprimarily carbon monoxide. Because pure carbon is more reactive at thehigh operating temperatures than the carbon monoxide gas, additionaloxygen injected into the vessel 20 should react with the carbon and formcarbon monoxide, and not with the carbon monoxide to form carbon dioxide(assuming that the oxidant is not added in excess). Carbon dioxide isalso relatively less stable at the high pyrolysis temperatures thancarbon monoxide.

After the oxidant is injected into the system through injectors 45,turbulence can be created to thoroughly mix the carbon and steam tofacilitate gasification of the carbon. The vessel 20 includes aturbulent region 104 and the gas vent 40 includes a turbulent region 47into which the oxidant can be injected and through which the exiting gasand entrained carbon can be forced to pass. The carbon and oxidantdesirably can remain in the turbulent region for an amount of timesufficient to maximize the oxidation reaction.

The residence time is the amount of time that the gas and entrainedparticulate and steam remain in the high temperature region of thevessel 20 and the off-gas piping (i.e. the gas vent 40 and piping 26).Residence time can be a function of the system volume and geometry, gasflow rate, and the distance the gas travels. At the highest gas flowrate, the volume of the vessel 20, turbulent regions 104 and 47 and theoff-gas piping that carries the gas to the ejector-venturi quencher 65should provide a sufficient residence time for the complete dissociationof the organic materials and the oxidation reaction to occur. Theturbulent regions 104 and 47 can improve the probability of reactionbetween carbon and oxygen without having to increase the residence timeor the volume of the vessel 20 or off-gas piping.

The amount of oxidant added through the injectors 45 can be closelycontrolled, because excess oxygen in the system may cause combustion tooccur, which can lead to the formation of carbon dioxide (which has nofuel value). In addition, excess oxygen can undesirably lead to theformation of compounds such as polyaromatic hydrocarbons, dioxins, andfurans.

The proper amount of oxidant injected through the injectors 45 can bedetermined through two alternative means. Generally, the amount ofoxidant needed to achieve the desired gasification of the particulatecarbon can be determined by monitoring the percentages of carbonmonoxide, carbon dioxide, and methane in the product gas stream. Thiscan be accomplished by a second gas monitor 52 (further describedbelow). As the waste composition in the feed varies, however, temporary,rapid changes can occur in the amount of carbon particulate entrained inthe gas leaving the pyrolysis vessel 20. Accordingly, an immediateadjustment in the amount of oxidant injected through the injectors 45 issometimes required to respond to such surges. In this situation, theproper amount of oxidant injected through the injectors 45 can bedetermined downstream with a particulate monitoring system.

FIG. 3 illustrates an exemplary particulate monitoring system of thewaste processing system 5, a first gas monitor 51. The first gas monitor51 can measure the amount of free carbon in the gas stream as it exitsthe pyrolysis vessel 20. The first gas monitor 51 can include a taphaving small viewing holes 56 in the refractory lining of the outlet gaspiping 26 from the vessel 20. The viewing holes 56 can be fitted withstainless steel pipes 57, water-cooled jackets 58 surrounding the pipes,nitrogen purge ports 59, glass pressure windows 60, a light source 64and a detector 62.

The detector 62 can continuously monitor the gas leaving the pyrolysisvessel 20 to measure carbon particulate. Light of a specified wavelengthfrom the light source 64 travels across the gas pipe 26 to the detector62. The amount of light that reaches the detector 62 can be dependent onthe density of the carbon particulate in the gas traveling through thepipe 26. The carbon particulate causes scattering and dispersion of thelight emitted from the light source 64.

The output from the detector 62 goes to a signal processor 63 connectedto the process monitor and controls 50. The process monitor and controls50 (see also FIG. 1) desirably includes a programmable logic controllerhaving an imbedded microprocessor, and various controls and monitoringdevices, which can control the amount of steam injected through theinjectors 45.

In operation, the detector 62 can identify surges of carbon particulatein the gas stream that can follow the rapid decomposition of organicmaterial and sends a corresponding signal to the signal processor 63,which processes the signal and directs it to the logic devices of theprocess monitor and controls 50. The logic devices control the openingof the steam valve 54 to cause oxidant to be immediately injectedthrough the injectors 45 until an acceptable carbon particulate levelhas been restored. The waste processing system 5 thus achieves a balancebetween the amount of liberated carbon and the amount of oxygenpermitted to react with it. An exemplary acceptable carbon particulatelevel is about 30 grains/scf.

Referring to FIG. 2, the gas (i.e. mostly hydrogen gas, carbon monoxidegas, and/or hydrogen chloride gas) formed from the dissociation andpartial oxidation of the organic portion of the waste can be heated toat least about 900° C. to 1150° C. in the vessel 20. This gas, called asynthesis gas, can be drawn out of the vessel 20 through the outlet 105by the vacuum created by the downstream draft fan 19 (shown in FIG. 1).After exiting the vessel 20, the synthesis gas travels through the gasvent 40 and then through the piping 26. The gas vent 40 and piping 26can be designed to convey the synthesis gas at a temperature of betweenabout 875° C. and 1350° C. to the ejector-venturi quencher 65. Forexample, the gas vent 40 and gas pipe 26 may be refractory lined andthermally insulated. In addition, the gas vent 40 and gas pipe 26 can bedesigned to be airtight to prevent the introduction of unwanted air intothe synthesis gas stream.

The gas is then rapidly cooled in the quencher 65 to a temperature ofless than about 150° C. The quencher 65 may be constructed of carbonsteel or a specialty metal, such as Hastelloy or other appropriatematerials, which can inhibit corrosion that may be caused by any acidicgases present in the synthesis gas. The quencher 65 may be lined withrefractory materials.

A spray nozzle is mounted at or near the top of the quencher 65 andsprays a scrubbing solution (such as water) down through the quencher65. The scrubbing solution is desirably introduced into the quencher 65at a rate of about 750 to 1,300 liters/minute. At this rate, a pressure(draft) can be created through the system, which can induce the flow ofgases away from the torches 35A and 35B and through the quencher 65. Inaddition, the feed rate creates a backpressure against the spray nozzle,which can help atomize the scrubbing solution into fine droplets. Finedroplets are desirable, because they provide increased surface area.

As the hot synthesis gas contacts the droplets, the scrubbing solutionis quickly heated and evaporative cooling quickly lowers the synthesisgas temperature to prevent or minimize the reformation of undesirablecomplex organic molecules. The atomized scrubbing solution can alsoremove inorganic particulates, heavy metals, and carbon particulatesentrained in the synthesis gas. These materials can be carried by thescrubbing solution by gravity into a scrubber recirculation tank 809(while the gas continues on through the waste treatment system 5).

The quencher 65 can provide several benefits. For example, the quencher65 can provide high turn-down ratios, which allows the system to operateeffectively at the low gas flows generated when processing inorganicmaterials and the high gas flows generated when processing highlyorganic materials. It can also provide a high particulate removalefficiency and inherent stability in terms of the gas temperaturefluctuations caused when processing combinations of waste streams, suchas medical waste, with a highly variant composition.

The quencher 65 can be located close to the vessel 20 to minimize heatloss and cooling until the gas reaches the quencher 65 and is rapidlycooled. High temperature thermocouples, for example, can monitor the gastemperature exiting the vessel 20 and downstream proximate to the inletof the quencher 65 to confirm that the synthesis gas reaches thequencher 65 at an appropriate temperature.

It is desirable to maintain the temperature of the synthesis gas aboveabout 1,000° C. before it is rapidly cooled in the quencher 65 tominimize or prevent the formation of hazardous or toxic substances suchas furans or dioxins. Various operating parameters can be used tomaintain the synthesis gas temperature within the preferred operatingrange. The operating gas temperature inside the vessel 20, for example,is at least partially a function of balancing the torch power input andthe waste material feed rate. The torches 35A and 35B provide theprincipal requisite amount of heat to ensure the molecular dissociationand to maintain a minimum bulk vessel temperature, which may bedeterminative of the gas temperature. The waste absorbs heat energy asit is fed into the vessel. Because the torch power can be primarilyfixed by its size and operating parameters, the waste feed rate andadditives (e.g., combination of organic/inorganic wastes) can be used toprevent the vessel 20 from overheating or under heating, and thereby toregulate the vessel/gas temperature.

Another parameter that can influence gas temperature is the amount ofcombustion/oxidation that occurs to form carbon dioxide. For example,injecting additional excess steam into the vessel 20 may allow a largerpercentage of carbon to oxidize to carbon dioxide (and carbon monoxideto oxidize to carbon dioxide). This reaction is exothermic, and itreleases additional heat, which tends to raise temperature. Thisreaction can be promoted to raise temperatures at the beginning of thewaste treatment process; however, it can lower the fuel quality of theend-product gas and, accordingly, it is a less desirable aspect of theprocess if the end-product gas is intended for productive use.

After the gas is cooled by the quencher 65, it is drawn by the draft fan19 into a means for neutralizing gaseous pollutants in the synthesisgas, such as acidic gases, and for separating any remaining inorganicparticulates, heavy metals, or carbon particulates entrained in thesynthesis gas. This means can be a scrubber 68, such as a conventionalpacked bed scrubber. The scrubber 68 can be comprised of a flow-throughvessel containing spray nozzles located at the top of the vessel and arandom or high performance packing that provides a close gas-liquidcontact. Water or water mixed with a neutralizing agent from theneutralizing agent supply 74 (e.g., sodium hydroxide) can be flowed fromthe nozzles downward by gravity over the packing as the gases are flowedupward through the packing. Hydrogen chloride gas, for example, whichwas formed in the vessel 20, can be neutralized in the scrubber 68 byreacting it with a basic neutralizing agent to form salts while the gastravels through the scrubber 68. The blowdown from the scrubber 68 cancollect in the recirculation tank 809 along with the blowdown from thequencher 65.

Most of the blowdown from the quencher 65 and scrubber 68 that collectsin the tank 809 can be recirculated to the quencher 65 and scrubber 68.A portion of the blowdown, however, can be flowed (by gravity or pump)to a wastewater treatment system 72. A water supply 73 and aneutralizing agent supply 74 supply regulated amounts of water and aneutralizing agent (e.g., sodium hydroxide) to the recirculation tank809 to make up for the blowdown flowed to the wastewater treatmentsystem 72.

In the wastewater treatment system 72, the particulate matter can beconcentrated, for example, by allowing the particulate to settle and/oradding a floculant that causes the particulate to agglomerate and formlarger particles. The particulate can then be transferred to aparticulate recycling system 66 and/or discharged to a sewer 75. In theparticulate recycling system 66, a filter press can be used to removethe water (or scrubbing solution) from the particulate and form aparticulate cake. The cake may be introduced back into the feedingsystem 10 to be reprocessed or it can be combined with another wastestream to be processed.

After the synthesis gas leaves the scrubber 68, it can pass the secondgas monitor 52, which comprises an on-line gas monitor for monitoringthe composition of the synthesis gas. The gas monitor 52 can include athermal conductivity analyzer 76 to measure the percentage of hydrogen,and at least one infrared analyzer 77 to measure the percentages ofcarbon monoxide, carbon dioxide, and methane. These measurements can berepresentative of the total hydrocarbons in the synthesis gas. Theanalyzers 76 and 77 provide a general measure of the proportions ofcarbon and oxygen in the gas and this measure can be used for monitoringoverall process balance and for generally determining the proper amountof oxidant to be injected through injectors 45, as discussed above.Generally speaking, the higher the amount of unreacted carbonparticulate detected in the synthesis gas, the higher the amount ofoxidant that should be injected through the injectors 45.

In addition, the second gas monitor 52 can be used to determine if thereare any air leaks in the system. Such leaks can be indicated by lowtotal percentages of hydrogen, carbon monoxide, carbon dioxide andmethane. If air, being about 80% nitrogen, is leaking into the system,the total percentage of the four gases can be less than approximately92-94%. The gas percentages can also indicate that the system isoperating properly.

After the synthesis gas passes the second gas monitor 52, it can bedrawn through the draft fan 19 and then monitored by a venturi flowmeter 19A, which measures the gas differential pressure. In thealternative, the meter 19A may be located before or together with thefan 19. The measurements from the meter 19A may be sent to the processmonitor and controls 50, which can calculate the volumetric gas flowrate. This rate can be used to help set the overall control settings forprocessing waste materials. For example, the rate can indicate whetherthe system is operating in a manner that exceeds its capacity. If thesystem is operated above capacity, the waste materials may not becompletely treated or destroyed, which can lead to undesirable pollutantemissions. Exemplary flow rates are about 4,000 to about 20,000 STDcubic feet per hour for a system processing 5 tpd of materials.

Generally speaking, the process monitor and controls 50 can monitorprocess variables that can be subsequently used to control other processvariables to achieve the desired end product of the waste treatmentprocess. The waste processing system 5, for example, can be designed tocontrol the reformation of the organic compounds from the dissociatedelemental components. This can be achieved, for example, by controllingvarious process temperatures and pressures and also the injection of anoxidant into the system. Desirably, the waste processing system 5maximizes the percentages of hydrogen and carbon monoxide, and minimizesthe percentages of carbon dioxide, carbon particulate, and reformedcomplex organic compounds in the synthesis gas.

The synthesis gas exiting the meter 19A may then be transported to aknown conventional energy recovery system 70 (i.e. a system thatutilizes the energy of the synthesis gas). The resulting clean fuel gascan be mostly hydrogen and carbon monoxide and, more particularly, canbe roughly about 45-55% hydrogen gas and about 30-40% carbon monoxidegas. The gas can be used as a fuel for steam or electricity generatingequipment or the hydrogen can be extracted as a clean fuel or precursorin many important manufacturing processes (e.g., plastics and methanolproduction). In addition, as an alternative to natural gas forelectricity production, the resulting clean fuel gas produced asdescribed herein has the ability to help preserve valuable fossil fuels.

FIGS. 4-7 represent flow diagrams of exemplary methods for treatingwaste, such as with the above-described waste treatment system 5. Itshould be understood, however, that the method steps illustrated by theblocks in these figures may be performed in other sequences, other stepsmay be added, and/or one or some of the steps may be skipped, deleted,or performed simultaneously with another step or other steps. Inaddition, the method steps may be carried out in a waste treatmentsystem other than the systems described herein.

FIG. 4 is a block diagram showing an exemplary way of treating waste,such as with the waste treatment system 5. At block 402, a torch isprovided. The torch can be a plasma torch, and, specifically, an ACplasma torch. At block 404, waste is provided. At block 406, a flame isgenerated with the torch. The flame may be generated, for example, withnitrogen as the torch gas. At block 408, the flame is adjusted. Theflame can be adjusted, for example, depending on the characteristics ofthe waste to be treated. At block 410, the waste is heated with energyfrom the flame.

FIG. 5 is a block diagram showing a first exemplary way to treat thewaste after the waste is heated. At block 502, the waste is melted orvitrified. At block 504, the waste forms a pool and, at block 506, thewaste is quenched. At block 508, the waste is transported and, at block510, the waste is disposed.

FIGS. 6A and 6B are a block diagram showing a second exemplary way totreat waste after the waste is heated. At block 602, the waste isdissociated into elemental components. This dissociation can destroy thehazardous constituency of at least part of the waste and can beaccomplished through pyrolysis of the waste. At block 604, the waste isgasified. At block 606, the elemental components are reformed as carbonmonoxide gas and hydrogen gas. At block 608, oxygen is provided and, atblock 610, the oxygen is combined with the elemental components to formcarbon monoxide gas.

As shown on FIG. 6B, at block 612, the carbon monoxide gas and hydrogengas is cooled. At block 614, any carbon particulate entrained in thecarbon monoxide gas and hydrogen gas is removed. At block 616, any acidgases in the synthesis gas are neutralized. Finally, at block 618, theenergy from the carbon monoxide gas and hydrogen gas is recovered.

FIG. 7 shows a further exemplary method for treating waste, such as withthe waste treatment system 5. At block 702, waste is provided that hasan inorganic portion and an organic portion. At block 704, a vessel withan AC plasma torch mounted therein is provided. At block 706, the wasteis introduced into the vessel. This can be done at a controlled,continuous rate, or at some other rate.

At block 708, a flame is generated with the AC plasma torch. At block710, the energy from the flame is used to heat the waste. At block 712,the inorganic portion of the waste is melted or vitrified, for example,as a result of the energy from the flame. At block 714, the organicportion of the waste is gasified and dissociated, for example, as aresult of the energy from the flame. The acts of melting or vitrifyingthe waste and gasifying or dissociating the waste illustrated by blocks712 and 714 can occur simultaneously or non-simultaneously.

The waste processing system 5 described herein can process a widevariety of hazardous and non-hazardous, inorganic and organic, materialscontaining varying amounts of moisture, and simultaneously comply withall, most, or some of the applicable air and water emissions standards.The waste treatment system 5 can maintain a constant high temperature inthe pyrolysis vessel 20 and control the temperature of the synthesis gasto produce an end product containing minimal hazardous organic moleculesand that can be productively used. In addition, the waste treatmentsystem 5 can produce solid residues in the form of glass-containedmetals which can pass TCLP tests and, accordingly, can be recycled orreused.

The methods and apparatus described herein can differ from known methodsand apparatus involving combustion (incineration). The waste processingsystem 5 described herein can utilize energy from a torch, such as an ACplasma torch, to thermally decompose waste through pyrolysis (anoxygen-starved process). Incinerators, on the other hand, use combustionto create energy (heat) to propagate the continued destruction of thewaste material (an oxygen-required process). In addition, the wasteprocessing system 5 described herein generally does not generatehazardous bottom ash, fly ash, dioxin, or furan, all of which arecommonly found in or created by incinerators.

The foregoing description of the invention has been presented toillustrate the principles of the invention and not to limit theinvention to any particular embodiment illustrated. It is thereforeintended that the foregoing detailed description be regarded asillustrative rather than limiting, and that it be understood that it isthe following claims, including all equivalents, that are intended todefine the spirit and scope of this invention.

1. An apparatus for treating waste comprising: (a) a vessel; and (b) atleast two plasma torches mounted with the vessel, wherein at least oneof the plasma torches emits a flame which is adjusted according to thewaste being treated.
 2. The apparatus for treating waste of claim 1wherein the at least two plasma torches are comprised of DC plasmatorches.
 3. The apparatus for treating waste of claim 1 wherein the atleast two plasma torches are comprised of at least one DC plasma torchand at least one AC plasma torch.
 4. The apparatus for treating waste ofclaim 3 wherein the vessel contains an open space and wherein the plasmatorches are mounted with the vessel such that they do not penetrate theopen space.
 5. The apparatus for treating waste of claim 4 furthercomprising at least one door that can separate at least one of theplasma torches from the open space in the vessel.
 6. The apparatus fortreating waste of claim 3 wherein flames from the at least two plasmatorches are generated simultaneously.
 7. The apparatus for treatingwaste of claim 3 further comprising a feeding system connected to thevessel comprising a charging hopper and a feeding hopper, wherein thefeeding hopper includes an airlock door on a side through which wastecan be introduced into the feeding hopper.
 8. The apparatus for treatingwaste of claim 7 further comprising a purging system connected with thefeeding system.
 9. The apparatus for treating waste of claim 7 furthercomprising a disinfectant system connected with the feed system.
 10. Theapparatus for treating waste of claim 9 further comprising at least twotaps positioned in the vessel.
 11. The apparatus for treating waste ofclaim 10 further comprising an access and viewing port on the vessel.12. The apparatus for treating waste of claim 11 further comprising anoxidant within the vessel.
 13. The apparatus for treating waste of claim12 further comprising: (a) a venturi flow meter connected with thevessel.
 14. The apparatus for treating waste of claim 13 furthercomprising: (a) a quencher connected with the vessel; (b) arecirculation tank connected with the quencher; (c) a scrubber connectedto the recirculation tank; (d) a water supply system connected to therecirculation tank; and (e) a neutralizing agent supply system connectedto the recirculation tank.
 15. The apparatus for treating waste of claim14 further comprising: (a) a wastewater treatment system connected withthe recirculation tank; and (b) a particulate recycling system connectedwith the wastewater treatment system.
 16. A method for treating wastecomprising: (a) providing at least two DC plasma torches with variableflames; (b) providing waste; (c) adjusting the flames in accordance witha type of waste to be treated; and (d) heating the waste with energygenerated by the flames.
 17. The method for treating waste according toclaim 16 wherein the waste is comprised of solid waste and liquid waste.18. The method for treating waste according to claim 17 furthercomprising: (a) melting or vitrifying the waste; (b) forming a pool ofthe melted or vitrified waste; and (c) quenching the melted or vitrifiedwaste.
 19. The method for treating waste according to claim 17 furthercomprising: (a) dissociating the waste into elemental components; (b)gasifying the waste; and (c) reforming the elemental components ascarbon monoxide gas and hydrogen gas.
 20. The method for treating wasteaccording to claim 19 wherein the step of dissociating the wastedestroys the hazardous constituency of at least part of the waste and isaccomplished through pyrolysis of the waste.
 21. The method for treatingwaste according to claim 19 further comprising: (a) providing oxygen;and (b) combining the oxygen with the elemental components to formcarbon monoxide gas.
 22. The method for treating waste according toclaim 21 further comprising: (a) providing excess oxygen; and (b)combining the oxygen with the elemental components to form carbondioxide gas.
 23. The method for treating waste according to claim 22further comprising: (a) cooling the carbon monoxide gas and hydrogengas; (b) removing carbon particulate from the carbon monoxide gas andhydrogen gas; and (c) neutralizing any acid gases contained with thecarbon monoxide gas and hydrogen gas.
 24. A method for treating wastecomprising: (a) providing a DC torch with a variable flame; (b)providing waste; (c) adjusting the flame in accordance with a type ofwaste to be treated; (d) adding a reducing agent or fluxing agent to thewaste before performing step (e); and (e) heating the waste with energygenerated by the flame.
 25. The method for treating waste according toclaim 24 wherein the treatment of the waste results in a synthesis gaswith about 45-55% hydrogen gas and about 30-40% carbon monoxide gas. 26.A method for treating waste comprising: (a) providing waste, wherein thewaste includes an inorganic portion and an organic portion; (b)providing a vessel with at least two plasma torches mounted therein,wherein one of the plasma torches is a DC plasma torch and one is an ACplasma torch; (c) introducing the waste into the vessel; (d) generatinga flame with at least one of the plasma torches; (e) varying the flameaccording to the waste being treated; and (f) heating the waste with theenergy from the flame.
 27. The method for treating waste according toclaim 26 further comprising: (a) melting or vitrifying the inorganicportion of the waste; and (b) gasifying and dissociating the organicportion of the waste.
 28. The method for treating waste according toclaim 27 wherein the steps (a) and (b) are performed simultaneously.